It has already been suggested to provide a caseband for a wristwatch case formed from a contoured strip. Swiss patent document CH-A-492 244 describes a mass production method of manufacturing watch cases from a contoured strip having a rectangular cross-section. In this method one begins by piercing pilot holes in the strip, such holes providing means for driving and centering for all subsequent operations. Next a cap is formed by cold pressing by means of a die and punch, such cap forming the case of the watch. Attachment lugs are struck out by punching, the crystal snap is machined by turning, one proceeds to arching of the lugs, then the holes necessary to accommodate the winding stem and the bracelet attaching bars are pierced. Finally, the case is separated from the strip. The entire process is brought about by an installation permitting a step by step advance of the strip and positioning thereof at each work station.
The watch case thus obtained has however several disadvantages. Initially, it may be said to show a mediocre aspect since the case and in particular the bezel which surrounds the crystal are obtained from a flat strip having no particular decoration. Next there is the disadvantage of requiring costly retouching operations if only for fastening the crystal and/or the case back, if a removable case back is considered indispensable for access to the watch mechanism. Finally, there is the disadvantage of requiring the employment of attachment bars for the bracelet at least in the embodiment as proposed.
It has also been suggested to mass produce a case band from a contoured strip extruded in the form of a tube. British patent document GB-A-887 130 shows such an arrangement where, after having attached lugs by welding along the tube, such tube is cut into slices to obtain the desired caseband. This system is relatively expensive to put into practice and above all does not permit obtaining directly from the contour a structure in relief elongated in the sense in which the contour is drawn, since the contour of the cited document comprises a tube and not a strip as in the present invention.
French patent document FR-A-2 329 002 describes a watchcase including a bezel formed from folded sheet metal including two attaching ridges thanks to which may be assembled a crystal and a back cover-container. Herein there is found no structure in relief which could be obtained from a contoured profile as is the case in the present invention.